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Prevalence of hepatitis C virus infection in the general population and patients with liver disease in China
Hepatology Research 14 (1999) 135 – 143
Prevalence of hepatitis C virus infection in the general population and patients with liver disease in China Lei Xuezhong a, Shigeko Naitoh b, Deng Xuewen b, Wang Song a, Qin San a, Liu Li a, Tang Hong a, Zhao Liansan a, Lei Bingjun a, Yoshihiro Akahane b,* a Department of Infectious Diseases, The First Uni6ersity Hospital of West China Uni6ersity of Medical Sciences, Chengdu, China b The First Department of Internal Medicine, Yamanashi Medical Uni6ersity, Yamanashi-Ken, Japan
Received 31 July 1998; received in revised form 28 November 1998; accepted 15 December 1998
Abstract Universal vaccination of newborns and high-risk populations, along with guidelines for prevention, has decreased the morbidity of hepatitis B virus (HBV) infection dramatically during the past few years in China. This, however, has revealed a hidden risk of hepatitis C virus (HCV) infection. Hence, the epidemiology of HCV infection in the general population and hepatitis patients was surveyed for planning the strategy to prevent HCV infection in China. The overall prevalence of antibody to HCV (anti-HCV) in the general population was 3.1% (63/2011) in cross-section studies performed in September, 1993 and 2.4% (38/1586) in January, 1996. During this period, 14 of 517 (2.7%) cases contracted HCV infection. Anti-HCV was detected in 31 of the 436 (7.1%) patients with chronic liver disease and 41 of the 169 (24.3%) patients with hepatocellular carcinoma. Of the 61 patients who received transfusions, 15 (25%) seroconverted to anti-HCV. These results indicate a significant role of HCV in inducing chronic liver disease leading to hepatocellular carcinoma, as well as a high risk of post-transfusion HCV infection, and warrant effective measures to be taken for decreasing the morbidity of HCV infection in China. © 1999 Elsevier Science Ireland Ltd. All rights reserved.
* Corresponding author. Tel.: +81-552-739584; fax.: + 81-552-736748. 1386-6346/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 1 3 8 6 - 6 3 4 6 ( 9 8 ) 0 0 1 1 9 - 3
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Keywords: Chronic liver disease; Hepatitis C virus; Hepatitis B virus; Hepatocellular carcinoma; Southwest China
1. Introduction In China, hepatitis B virus (HBV) was the major cause of liver disease during the past few decades [1 – 4]. The nationwide vaccination program for newborns and populations at increased risk for HBV infection, together with education of the general public to avoid infection, has controlled HBV infection. The decrease of de novo HBV infection, however, has revealed a risk for hepatitis C virus (HCV) infection which was hidden behind a hyperendemicity for HBV in China. Soon after the identification of HCV and the development of tests for antibody to HCV (anti-HCV), it has become increasingly evident that chronic HCV infection played a significant role in chronic liver disease ranging to hepatocellular carcinoma (HCC) [5 – 8]. Unsuccessful vaccine development and paucity of knowledge on the exact routes of transmission make the prevention of HCV infection still insufficient; HCV is prevalent worldwide with a frequency estimated at least 1% [9–12]. In order to comprehend the current status of HCV infection in Southwest China, survey for anti-HCV was performed on various populations between September, 1993 and June, 1997.
2. Materials and methods
2.1. Studied populations Staff members and patients in the Hospital of Stomatology in West China University of Medical Sciences (WCUMS) were surveyed for HCV infection. Cross-sectional surveys were performed on 3080 individuals at two time points, including 2011 in September, 1993 and 1586 in January, 1996. All the hospitalized patients at that time, were enrolled in this study, along with controls who were medical staffs and rear-service personnel, as well as their families and medical students of stomatology. For a prospective survey, 517 individuals negative for anti-HCV at the first cross-sectional study were followed for de novo HCV infection until the second cross-sectional study. In addition, 436 patients with chronic liver disease (CLD) were studied who visited Viral Hepatitis Clinic in the First University Hospital of WCUMS during October, 1995 through December, 1995 as well as 169 patients with HCC whose serum samples were collected between August, 1995 and March, 1997. Also, the 61 surgical patients who received transfusions during a period from October, 1993 to November, 1994 entered the present study. Chronic liver disease was diagnosed by sign and symptoms, abnormal liver function tests persisting for at least 6 months. The diagnosis of HCC was based on
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clinical examination, tumor markers, ultrasonic examination, computed tomography or magnetic resonance imaging; the diagnosis was further confirmed in 39 of the 61 (64%) patients with HCC by histopathological changes in liver tissue specimens obtained at liver biopsy or surgical operation. The prospective study was performed on the patients living in Chengdu who were negative for both anti-HCV and HCV RNA before blood transfusion. In a follow-up study, serum samples were collected from 517 cases at September, 1993 and January, 1996. A perspective study for post-transfusion hepatitis C was carried out on 61 cases who were followed for at least 6 months and from whom serum samples were collected 1, 2, 3–4, and 5–6 months after blood transfusions. All follow-up samples were tested for markers of HCV and/or HBV infection. The demographic and clinical characteristics of studied populations are shown in Table 1. The study was approved by the ethics committee of hospitals, and all subjects were 18 years or older and gave an informed consent.
2.2. Markers of hepatitis 6irus infections All the serum samples were collected with great care for avoiding contamination, stored at −20°C and tested by the same technicians. In the prospective study for post-transfusion hepatitis C, samples from the donated blood units were stored and tested for tracing the source of HCV infection. Anti-HCV was tested by commercially available enzyme immunoassay (EIA of the second generation, Sumitomo Metal Industries, Tokyo, Japan and Hua Yi Biotechnic Company, Beijing, China). Serum samples from the cohorts for prospective studies were tested, in addition, for HCV RNA by reverse-transcription polymerase chain reaction (Hua Mei Biotechnic Company, Beijing, China). The measures to avoid contamination recommended by Kwok and Higuchi were followed as strictly as possible [13]. Commercial assay kits (Mycell: Institute of Immunology, Tokyo, Japan) were used for the detection of hepatitis B surface antigen (HBsAg) by reversed passive hemagglutination and Table 1 Demographics and clinical status of studied subjects Populations
General population (cross-sectional) September, 1993 January, 1996 Follow-up Patients a CLD HCC Surgical a
Age in years
Gender
Mean (range)
Male/Female
2011 1586 517
43.6 (18–76) 41.2 (18–75) 46.3 (18–73)
1023/988 8675/721 287/230
436 169 61
38.6 (27–65) 53.5 (36–76) 47.2 (25–60)
295/141 140/29 34/27
N
CLD, chronic liver disease; HCC, hepatocellular carcinoma.
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Table 2 Prevalence and incidence of HCV infection in the general population and patients Subpopulations
Medical staffs Paramedical Family members Students Patients Total a
Cross-sectional
Follow-up
September, 1993
January, 1996
1993–1996
17/947 (1.8%) 11/286 (3.8%) 23/570 (4.0%) 4/193 (2.1%) 8/215 (3.7%) 63/2011 (3.1%)a
11/485 (2.3%) 6/196 (3.1%) 10/473 (2.1%) 6/334 (1.8%) 5/93 (5.4%) 38/1586 (2.4%)
4/248 (1.6%) 1/82 (1.2%) 4/105 (3.8%) 3/69 (4.3%) 2/13 (15%) 14/517 (2.7%)
Higher than the prevalence in January, 1996 (PB0.05).
antibody to HBsAg (anti-HBs) by passive hemagglutination. Hepatitis B core antibody (anti-HBc) was determined by hemagglutination inhibition. Hepatitis B e antigen (HBeAg) and the antibody to it, (anti-HBe) were tested by kits with enzyme immunoassay (HBeAg/Ab EIA: Institute of Immunology).
2.3. Statistical analysis Frequencies between groups were compared by the two-tailed Mantel-Haenszel chi-square test or two-tailed Fisher’s exact test. Non-conditional logistic regression analysis was performed on subgroups of general population for confounding variables by EGRET software. P values of less than 0.05 were considered to indicate a statistical significance.
3. Results
3.1. HCV infection in the general population In the cross-sectional studies performed in the Hospital of Stomatology of WCUMS at two time points (September, 1993 and January, 1996), anti-HCV was detected in 63 of 2011 (3.1%) individuals and 38 of 1586 (2.4%) individuals, respectively (Table 2). During a follow-up for 28 months in the cohort study, the morbidity of HCV infection was identified in 14 of the 517 (2.7%). There were no significant differences in the prevalence of HCV infection between the two crosssectional studies (P B 0.185) and among subgroups of the general population (P\ 0.05).
3.2. Markers of HBV and HCV infections in the patients with CLD Of the 436 patients with CLD, 277 (64%) were HBsAg positive, of whom 67 (15%) were positive also for HBeAg. Anti-HBc was detected in 325 (75%) patients,
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while only 46 (11%) were positive for anti-HBs (Table 3). Anti-HCV was detected in 31 (7%) patients, and 15 of them were co-infected with HBV. There were 43 (10%) patients with CLD who had no serum markers of HBV or HCV infection.
3.3. HBV and HCV infection in the patients with HCC As shown in Table 3, anti-HCV was detected in 41 of the 169 (24%) patients with HCC, of whom 31 had the co-infection with HBV. HBsAg was positive in 126 (75%) patients with HCC. This left 16 (10%) patients who were negative for markers of HBV or HCV infection (non-B, non-C). The prevalence of HCV infection was significantly higher in the patients with HCC than that in the general population and the patients with CLD (PB 0.0001).
3.4. Incidence of post-transfusion hepatitis C During October, 1993 through November, 1994, 61 patients received transfusions and followed in Surgery Department of the First University Hospital of WCUMS. Within a 6-month follow-up, 15 of the 61 (25%) patients seroconverted to antiHCV, of whom ten were positive for HCV RNA; three possessed anti-HCV only and two had HCV RNA alone. There were additional four cases with transient anti-HCV which turned negative in the 2nd month of follow-up. All the four cases had no symptoms, and possessed normal levels of serum alanine aminotransferase. They were not included in the cases of post-transfusion HCV infection, because anti-HCV would have been transferred to them passively by transfusions. Markers of HCV infection was searched for in the blood units received by the 15 patients with post-transfusion HCV infection. Anti-HCV was detected in at least one of the blood units given to 12 of the 15 (80%) patients; only three (20%) received blood units without anti-HCV.
Table 3 Markers of HBV and HCV infections in the patients with chronic liver disease and those with hepatocellular carcinoma Markers
CLD (n=436)
HCC (n =169)
Differences
HBsAg Anti-HBs HBeAg Anti-HBc Anti-HCV Non-B, non-C
277 (64%) 46 (11%) 67 (15%) 363 (83%) 31 (7%) 43 (10%)
126 (75%) 6 (4%) 31 (18%) 141 (83%) 41 (24%) 16 (10%)
PB0.01 PB0.01 NSa NS PB0.0001 NS
a
Not significant.
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4. Discussion China was an area hyperepidemic for HBV infection, with an estimated carrier rate exceeding 10% of the general population [4,14]. However, the morbidity of HBV infection has decreased during the past few years, due not only to the hepatitis B vaccination program for all newborns implemented since January, 1992, as well as for populations at high risk of infection, but also to a wide distribution of knowledge for preventing HBV infection. Researches for assessing the efficacy of HBV vaccine are in progress, which would verify that the hepatitis B vaccination is a really powerful measure for blocking the transmission of HBV and for preventing the subsequent development of CLD. On the other hand, ample sero-epidemiological lines of evidence have shown that, worldwide, HCV is an important etiologic factor for liver disease and plays a significant role in the development of HCC [15–18]. Although few researches on the prevalence of HCV infection have been conducted in different Chinese populations during the past few years, the exact status of HCV infection has not been delineated for fully understanding the epidemiology of HCV and its association with CLD. In the present study, the overall prevalence of anti-HCV in the general Chinese population was 3.1% (63/2011) in September, 1993 and 2.4% (38/1586) in January, 1996, which were much higher than the reported prevalence of approximately 1% in many of the other countries [9 –11]. Moreover, a further cohort study showed a morbidity of HCV infection to be 2.7% (14/517) during a follow-up for 28 months. Likewise, another nationwide cross-sectional sero-epidemiological study of HCV infection, performed in China in 1992, suggests an overall prevalence of HCV infection at 3.2%; the prevalence is higher in North China division (3.0–6.0%) but lower in South China division (0.9–2.9%) [4]. Taken together, it can be estimated that there would be at least 38 million cases of HCV infection in China. Furthermore, it needs to be pointed out that because of unclear routes of HCV infection, except by blood transfusion, and no HCV vaccines available at present, HCV infection may become increasingly a serious public-health problem in China. Hence, much more attention should be directed to controlling HCV transmission in the general population in China. In our survey in 1997, 436 patients of chronic hepatitis and liver cirrhosis also, were tested for markers of HBV and HCV infection. HCV was found to be the etiologic factor in 7.1% (31/436) of them, which was surprisingly less often than that in the other countries [14,19–22]. There are two possibilities which may account for this difference. First, even though most hepatitis C patients referred to our clinic were asymptomatic, they were identified because of abnormal serum levels of alanine aminotransferase at liver function tests performed at the time of physical examination. In China today, however, it is still common for many people without any symptoms not to see a doctor or have a physical examination. Therefore, it is possible that only less than half of the HCV infection cases have been identified. Secondly, cases of HCV infection may be beginning to increase. Considering the prevalence of HCV infection in the general population at present, hepatitis C patients are expected to increase among the patients with CLD. Further studies are needed to evaluate this possibility.
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The prevalence of HCV infection was investigated in the 169 cases with definite diagnosis of HCC, of which 41 (24.3%) were proved to be positive for anti-HCV. The frequency was much higher than that in previous studies conducted in China a few years ago, in which HBV infection was found in most HCC cases, in contrast to HCV infection observed in less than 10% [23]. It indicated clearly that a role of HCV should not to be ignored in the hepato-carcinogenesis and that HCV would become another major risk factor for the development of HCC in China. During the past few years, it has been well proven that the HCV infection is blood-borne and spreads mainly (40–80%) by horizontal transmission, but there would be unknown significant risk factors [24–27]. It is reported, also, that the contribution of HCV infection to post-transfusion hepatitis varies widely in different countries [27 – 29]. In the present study, the incidence of post-transfusion hepatitis C was 24.6% (15/61), which strongly suggested that blood transfusion would be a very important route of HCV transmission in China. Moreover, another multi-centric prospective study, performed in the recipients of transfusions in five Chinese university hospitals in 1995, showed quit high rates of seroconversion to anti-HCV (data not shown), which also suggests a close relationship between HCV infection and blood transfusions in China. The present results indicate that, even though the anti-HCV screening of blood donors has been conducted since July, 1992 in China, much more strict measures for donor screening are urgently needed. The following steps should be important for preventing post-transfusion HCV infection. First, anti-HCV detection kits with higher sensitivity and specificity should be used for donor screening. Secondly, the blood donation from volunteers should be advocated strongly. As are preceded by excellent outcomes achieved in Japan, West Europe and the United States [30–33], reducing the incidence of post-transfusion hepatitis C may be a key issue to keep HCV infection under control in China. In conclusion, besides HBV infection, HCV infection is also endemic in China. Much more attention should be focused on this here-to-fore underestimated risk, lest another serious public-health problem should develop in the foreseeable future in China.
Acknowledgements The authors thank Professor Hiroshi Suzuki, the Dean of Yamanashi Medical University and the President of Miyakawa Memorial Research Foundation, for valuable help and encouragement. This study was supported, in part, by Chinese Medical Board of New York.
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[2] Qu ZY. An epidemiological study on the distribution of HBsAg and anti-HBs in China. Chin J Microbiol Immunol 1986;1:S0–39. [3] Tao QM, Wang Y, Du SC, Guo JP. Epidemiology of hepatitis B and C in China. In: Nishioka K, Suzuki H, Mishiro S, Oda T, editors. Viral Hepatitis and Liver Disease. Tokyo: Springer, 1994:412–5. [4] Xia GL, Liu CB, Cao HL, et al. Prevalence of hepatitis B and C virus infections in the general Chinese population. Results from a nationwide cross-sectional seroepidemiologic study of hepatitis A, B, C, D, and E virus infections in China, 1992. Int Hepatol Commun 1996;5:62 – 73. [5] Yano M, Yatsuhashi H, Inoue O, Inokuchi K, Koga M. Epidemiology and long term prognosis of hepatitis C virus infection in Japan. Gut 1993;34:S13 – 6. [6] Tsai JF, Jeng JE, Chang WY, Lin ZY, Tsai JH. Hepatitis C virus infection among patients with chronic liver disease in an area hyperendemic for hepatitis B. Scand J Gastroenterol 1994;29:550 – 2. [7] Bruix J, Barrera JM, Calvet X, et al. Prevalence of antibodies to hepatitis C virus in Spanish patients with hepatocellular carcinoma and hepatic cirrhosis. Lancet 1989;2:1004 – 6. [8] Plagemann PGW. Hepatitis C virus (review). Arch Virol 1991;120:165 – 80. [9] Rassam SW, Dusheiko GM. Epidemiology and transmission of hepatitis C infection (editorial). J Gastroenterol Hepatol 1991;3:585–91. [10] van der Poel CL, Reesink HW, Lelie PN, et al. Anti-hepatitis C antibodies and non-A, non-B post-transfusion hepatitis in The Netherlands. Lancet 1989;2:297 – 8. [11] Esteban JI, Gonzalez A, Hernandez JM, et al. Evaluation of antibodies to hepatitis C virus in a study of transfusion- associated hepatitis. New Engl J Med 1990;323:1107 – 12. [12] Chiaramonte M, Stroffolini T, Caporaso N, et al. Hepatitis-C virus infection in Italy: a multicentric sero-epidemiological study. Ital J Gastroenterol 1991;23:555 – 8. [13] Kwok S, Higuchi R. Avoiding false positives with PCR. Nature 1989;339:237 – 8. [14] Lee HS, Kim CY. Seroepidemiology of HBV and HCV in Korea: the decreasing prevalence rate of HBV infection after launching HB vaccination program. Int Hepatol Commun 1996;5:53 – 61. [15] Tong MJ, el-Farra NS, Reikes AR, Co RL. Clinical outcomes after transfusion-associated hepatitis C. New Engl J Med 1995;332:1463– 6. [16] De Bac C, Stroffolini T, Gaeta GB, Taliani G, Giusti G. Pathogenic factors in cirrhosis with and without hepatocellular carcinoma: a multicenter Italian study. Hepatology 1994;20:1225 – 30. [17] Lee HS, Han CJ, Kim CY. Predominant etiologic association of hepatitis C virus with hepatocellular carcinoma compared with hepatitis B virus in elderly patients in a hepatitis B-endemic area. Cancer 1993;72:2564–7. [18] Saito I, Miyamura T, Ohbayashi A, et al. Hepatitis C virus infection is associated with the development of hepatocellular carcinoma. Proc Natl Acad Sci USA 1990;87:6547 – 9. [19] Alter MJ, Mast EE. The epidemiology of viral hepatitis in the United States. Gastroenterol Clin North Am 1994;23:437–55. [20] Alter MJ. Epidemiology of hepatitis C in the West. Semin Liver Dis 1995;15:5 – 14. [21] Tandon BN, Acharya SK, Tandon A. Seroepidemiology of HBV and HCV in India. Strategy for control of maternal transmission of HBV and its effect. Screening methods of blood donors for control of post-transfusion hepatitis and their effects. Int Hepatol Commun 1996;5:14 – 8. [22] Suwignyo S. Seroepidemiology of hepatitis B and C in Indonesia. Int Hepatol Commun 1996;5:30 – 7. [23] Leung NW, Tam JS, Lai JY, et al. Does hepatitis C virus infection contribute to hepatocellular carcinoma in Hong Kong? Cancer 1992;70:40 – 4. [24] Wang JT, Wang TH, Lin JT, Sheu JC, Sung JL, Chen DS. Hepatitis C virus in a prospective study of post-transfusion non-A, non-B hepatitis in Taiwan. J Med Virol 1990;32:83 – 86. [25] Aach RD, Stevens CE, Hollinger FB, et al. Hepatitis C virus infection in post-transfusion hepatitis. An analysis with first- and second-generation assays. New Engl J Med 1991;325:1325– 9. [26] Peters T, Schlayer HJ, Preisler S, et al. Frequency of hepatitis C in acute post-transfusion hepatitis after open- heart surgery: a prospective study in 1476 patients. J Med Virol 1993;39:139 – 45. [27] Yoshizawa H, Watanabe J. Impacts of blood screening on the incidence of post-transfusion hepatitis C in Japan. Curr Stud Hematol Blood Transf 1994;61:182 – 94.
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[28] Nelson K, Ahmed F, Ness PM, et al. Efficacy of donor screening methods on reducing the risk of transfusion transmission of hepatitis C virus (HCV). Tokyo, Japan: Fourth International Symposium on HCV, May 7–9, 1993:40. [29] Sung JL. National strategies for viral hepatitis B, C and hepatocellular carcinoma in Taiwan. Int Hepatol Commun 1996;5:43–52. [30] Yoshizawa H. Blood screening to prevent post-transfusion hepatitis in Japan: effective for prevention as well as revealing for epidemiology of HBV and HCV infection in healthy subjects. Int Hepatol Commun 1996;5:79–87. [31] Donahue JG, Munoz A, Ness PM, et al. The declining risk of post-transfusion hepatitis C virus infection. New Engl J Med 1992;327:369 – 73. [32] Kleinman S, Busch M, Holland P. Post-transfusion hepatitis C virus infection (letter). New Engl J Med 1992;327:1601–2. [33] Holland PV. Viral infections and the blood supply (editorial). New Engl J Med 1996;334:1734 – 5.
.
Prevalence of hepatitis C virus infection in the general population and patients with liver disease in China Lei Xuezhong a, Shigeko Naitoh b, Deng Xuewen b, Wang Song a, Qin San a, Liu Li a, Tang Hong a, Zhao Liansan a, Lei Bingjun a, Yoshihiro Akahane b,* a Department of Infectious Diseases, The First Uni6ersity Hospital of West China Uni6ersity of Medical Sciences, Chengdu, China b The First Department of Internal Medicine, Yamanashi Medical Uni6ersity, Yamanashi-Ken, Japan
Received 31 July 1998; received in revised form 28 November 1998; accepted 15 December 1998
Abstract Universal vaccination of newborns and high-risk populations, along with guidelines for prevention, has decreased the morbidity of hepatitis B virus (HBV) infection dramatically during the past few years in China. This, however, has revealed a hidden risk of hepatitis C virus (HCV) infection. Hence, the epidemiology of HCV infection in the general population and hepatitis patients was surveyed for planning the strategy to prevent HCV infection in China. The overall prevalence of antibody to HCV (anti-HCV) in the general population was 3.1% (63/2011) in cross-section studies performed in September, 1993 and 2.4% (38/1586) in January, 1996. During this period, 14 of 517 (2.7%) cases contracted HCV infection. Anti-HCV was detected in 31 of the 436 (7.1%) patients with chronic liver disease and 41 of the 169 (24.3%) patients with hepatocellular carcinoma. Of the 61 patients who received transfusions, 15 (25%) seroconverted to anti-HCV. These results indicate a significant role of HCV in inducing chronic liver disease leading to hepatocellular carcinoma, as well as a high risk of post-transfusion HCV infection, and warrant effective measures to be taken for decreasing the morbidity of HCV infection in China. © 1999 Elsevier Science Ireland Ltd. All rights reserved.
* Corresponding author. Tel.: +81-552-739584; fax.: + 81-552-736748. 1386-6346/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 1 3 8 6 - 6 3 4 6 ( 9 8 ) 0 0 1 1 9 - 3
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Keywords: Chronic liver disease; Hepatitis C virus; Hepatitis B virus; Hepatocellular carcinoma; Southwest China
1. Introduction In China, hepatitis B virus (HBV) was the major cause of liver disease during the past few decades [1 – 4]. The nationwide vaccination program for newborns and populations at increased risk for HBV infection, together with education of the general public to avoid infection, has controlled HBV infection. The decrease of de novo HBV infection, however, has revealed a risk for hepatitis C virus (HCV) infection which was hidden behind a hyperendemicity for HBV in China. Soon after the identification of HCV and the development of tests for antibody to HCV (anti-HCV), it has become increasingly evident that chronic HCV infection played a significant role in chronic liver disease ranging to hepatocellular carcinoma (HCC) [5 – 8]. Unsuccessful vaccine development and paucity of knowledge on the exact routes of transmission make the prevention of HCV infection still insufficient; HCV is prevalent worldwide with a frequency estimated at least 1% [9–12]. In order to comprehend the current status of HCV infection in Southwest China, survey for anti-HCV was performed on various populations between September, 1993 and June, 1997.
2. Materials and methods
2.1. Studied populations Staff members and patients in the Hospital of Stomatology in West China University of Medical Sciences (WCUMS) were surveyed for HCV infection. Cross-sectional surveys were performed on 3080 individuals at two time points, including 2011 in September, 1993 and 1586 in January, 1996. All the hospitalized patients at that time, were enrolled in this study, along with controls who were medical staffs and rear-service personnel, as well as their families and medical students of stomatology. For a prospective survey, 517 individuals negative for anti-HCV at the first cross-sectional study were followed for de novo HCV infection until the second cross-sectional study. In addition, 436 patients with chronic liver disease (CLD) were studied who visited Viral Hepatitis Clinic in the First University Hospital of WCUMS during October, 1995 through December, 1995 as well as 169 patients with HCC whose serum samples were collected between August, 1995 and March, 1997. Also, the 61 surgical patients who received transfusions during a period from October, 1993 to November, 1994 entered the present study. Chronic liver disease was diagnosed by sign and symptoms, abnormal liver function tests persisting for at least 6 months. The diagnosis of HCC was based on
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clinical examination, tumor markers, ultrasonic examination, computed tomography or magnetic resonance imaging; the diagnosis was further confirmed in 39 of the 61 (64%) patients with HCC by histopathological changes in liver tissue specimens obtained at liver biopsy or surgical operation. The prospective study was performed on the patients living in Chengdu who were negative for both anti-HCV and HCV RNA before blood transfusion. In a follow-up study, serum samples were collected from 517 cases at September, 1993 and January, 1996. A perspective study for post-transfusion hepatitis C was carried out on 61 cases who were followed for at least 6 months and from whom serum samples were collected 1, 2, 3–4, and 5–6 months after blood transfusions. All follow-up samples were tested for markers of HCV and/or HBV infection. The demographic and clinical characteristics of studied populations are shown in Table 1. The study was approved by the ethics committee of hospitals, and all subjects were 18 years or older and gave an informed consent.
2.2. Markers of hepatitis 6irus infections All the serum samples were collected with great care for avoiding contamination, stored at −20°C and tested by the same technicians. In the prospective study for post-transfusion hepatitis C, samples from the donated blood units were stored and tested for tracing the source of HCV infection. Anti-HCV was tested by commercially available enzyme immunoassay (EIA of the second generation, Sumitomo Metal Industries, Tokyo, Japan and Hua Yi Biotechnic Company, Beijing, China). Serum samples from the cohorts for prospective studies were tested, in addition, for HCV RNA by reverse-transcription polymerase chain reaction (Hua Mei Biotechnic Company, Beijing, China). The measures to avoid contamination recommended by Kwok and Higuchi were followed as strictly as possible [13]. Commercial assay kits (Mycell: Institute of Immunology, Tokyo, Japan) were used for the detection of hepatitis B surface antigen (HBsAg) by reversed passive hemagglutination and Table 1 Demographics and clinical status of studied subjects Populations
General population (cross-sectional) September, 1993 January, 1996 Follow-up Patients a CLD HCC Surgical a
Age in years
Gender
Mean (range)
Male/Female
2011 1586 517
43.6 (18–76) 41.2 (18–75) 46.3 (18–73)
1023/988 8675/721 287/230
436 169 61
38.6 (27–65) 53.5 (36–76) 47.2 (25–60)
295/141 140/29 34/27
N
CLD, chronic liver disease; HCC, hepatocellular carcinoma.
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Table 2 Prevalence and incidence of HCV infection in the general population and patients Subpopulations
Medical staffs Paramedical Family members Students Patients Total a
Cross-sectional
Follow-up
September, 1993
January, 1996
1993–1996
17/947 (1.8%) 11/286 (3.8%) 23/570 (4.0%) 4/193 (2.1%) 8/215 (3.7%) 63/2011 (3.1%)a
11/485 (2.3%) 6/196 (3.1%) 10/473 (2.1%) 6/334 (1.8%) 5/93 (5.4%) 38/1586 (2.4%)
4/248 (1.6%) 1/82 (1.2%) 4/105 (3.8%) 3/69 (4.3%) 2/13 (15%) 14/517 (2.7%)
Higher than the prevalence in January, 1996 (PB0.05).
antibody to HBsAg (anti-HBs) by passive hemagglutination. Hepatitis B core antibody (anti-HBc) was determined by hemagglutination inhibition. Hepatitis B e antigen (HBeAg) and the antibody to it, (anti-HBe) were tested by kits with enzyme immunoassay (HBeAg/Ab EIA: Institute of Immunology).
2.3. Statistical analysis Frequencies between groups were compared by the two-tailed Mantel-Haenszel chi-square test or two-tailed Fisher’s exact test. Non-conditional logistic regression analysis was performed on subgroups of general population for confounding variables by EGRET software. P values of less than 0.05 were considered to indicate a statistical significance.
3. Results
3.1. HCV infection in the general population In the cross-sectional studies performed in the Hospital of Stomatology of WCUMS at two time points (September, 1993 and January, 1996), anti-HCV was detected in 63 of 2011 (3.1%) individuals and 38 of 1586 (2.4%) individuals, respectively (Table 2). During a follow-up for 28 months in the cohort study, the morbidity of HCV infection was identified in 14 of the 517 (2.7%). There were no significant differences in the prevalence of HCV infection between the two crosssectional studies (P B 0.185) and among subgroups of the general population (P\ 0.05).
3.2. Markers of HBV and HCV infections in the patients with CLD Of the 436 patients with CLD, 277 (64%) were HBsAg positive, of whom 67 (15%) were positive also for HBeAg. Anti-HBc was detected in 325 (75%) patients,
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while only 46 (11%) were positive for anti-HBs (Table 3). Anti-HCV was detected in 31 (7%) patients, and 15 of them were co-infected with HBV. There were 43 (10%) patients with CLD who had no serum markers of HBV or HCV infection.
3.3. HBV and HCV infection in the patients with HCC As shown in Table 3, anti-HCV was detected in 41 of the 169 (24%) patients with HCC, of whom 31 had the co-infection with HBV. HBsAg was positive in 126 (75%) patients with HCC. This left 16 (10%) patients who were negative for markers of HBV or HCV infection (non-B, non-C). The prevalence of HCV infection was significantly higher in the patients with HCC than that in the general population and the patients with CLD (PB 0.0001).
3.4. Incidence of post-transfusion hepatitis C During October, 1993 through November, 1994, 61 patients received transfusions and followed in Surgery Department of the First University Hospital of WCUMS. Within a 6-month follow-up, 15 of the 61 (25%) patients seroconverted to antiHCV, of whom ten were positive for HCV RNA; three possessed anti-HCV only and two had HCV RNA alone. There were additional four cases with transient anti-HCV which turned negative in the 2nd month of follow-up. All the four cases had no symptoms, and possessed normal levels of serum alanine aminotransferase. They were not included in the cases of post-transfusion HCV infection, because anti-HCV would have been transferred to them passively by transfusions. Markers of HCV infection was searched for in the blood units received by the 15 patients with post-transfusion HCV infection. Anti-HCV was detected in at least one of the blood units given to 12 of the 15 (80%) patients; only three (20%) received blood units without anti-HCV.
Table 3 Markers of HBV and HCV infections in the patients with chronic liver disease and those with hepatocellular carcinoma Markers
CLD (n=436)
HCC (n =169)
Differences
HBsAg Anti-HBs HBeAg Anti-HBc Anti-HCV Non-B, non-C
277 (64%) 46 (11%) 67 (15%) 363 (83%) 31 (7%) 43 (10%)
126 (75%) 6 (4%) 31 (18%) 141 (83%) 41 (24%) 16 (10%)
PB0.01 PB0.01 NSa NS PB0.0001 NS
a
Not significant.
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4. Discussion China was an area hyperepidemic for HBV infection, with an estimated carrier rate exceeding 10% of the general population [4,14]. However, the morbidity of HBV infection has decreased during the past few years, due not only to the hepatitis B vaccination program for all newborns implemented since January, 1992, as well as for populations at high risk of infection, but also to a wide distribution of knowledge for preventing HBV infection. Researches for assessing the efficacy of HBV vaccine are in progress, which would verify that the hepatitis B vaccination is a really powerful measure for blocking the transmission of HBV and for preventing the subsequent development of CLD. On the other hand, ample sero-epidemiological lines of evidence have shown that, worldwide, HCV is an important etiologic factor for liver disease and plays a significant role in the development of HCC [15–18]. Although few researches on the prevalence of HCV infection have been conducted in different Chinese populations during the past few years, the exact status of HCV infection has not been delineated for fully understanding the epidemiology of HCV and its association with CLD. In the present study, the overall prevalence of anti-HCV in the general Chinese population was 3.1% (63/2011) in September, 1993 and 2.4% (38/1586) in January, 1996, which were much higher than the reported prevalence of approximately 1% in many of the other countries [9 –11]. Moreover, a further cohort study showed a morbidity of HCV infection to be 2.7% (14/517) during a follow-up for 28 months. Likewise, another nationwide cross-sectional sero-epidemiological study of HCV infection, performed in China in 1992, suggests an overall prevalence of HCV infection at 3.2%; the prevalence is higher in North China division (3.0–6.0%) but lower in South China division (0.9–2.9%) [4]. Taken together, it can be estimated that there would be at least 38 million cases of HCV infection in China. Furthermore, it needs to be pointed out that because of unclear routes of HCV infection, except by blood transfusion, and no HCV vaccines available at present, HCV infection may become increasingly a serious public-health problem in China. Hence, much more attention should be directed to controlling HCV transmission in the general population in China. In our survey in 1997, 436 patients of chronic hepatitis and liver cirrhosis also, were tested for markers of HBV and HCV infection. HCV was found to be the etiologic factor in 7.1% (31/436) of them, which was surprisingly less often than that in the other countries [14,19–22]. There are two possibilities which may account for this difference. First, even though most hepatitis C patients referred to our clinic were asymptomatic, they were identified because of abnormal serum levels of alanine aminotransferase at liver function tests performed at the time of physical examination. In China today, however, it is still common for many people without any symptoms not to see a doctor or have a physical examination. Therefore, it is possible that only less than half of the HCV infection cases have been identified. Secondly, cases of HCV infection may be beginning to increase. Considering the prevalence of HCV infection in the general population at present, hepatitis C patients are expected to increase among the patients with CLD. Further studies are needed to evaluate this possibility.
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The prevalence of HCV infection was investigated in the 169 cases with definite diagnosis of HCC, of which 41 (24.3%) were proved to be positive for anti-HCV. The frequency was much higher than that in previous studies conducted in China a few years ago, in which HBV infection was found in most HCC cases, in contrast to HCV infection observed in less than 10% [23]. It indicated clearly that a role of HCV should not to be ignored in the hepato-carcinogenesis and that HCV would become another major risk factor for the development of HCC in China. During the past few years, it has been well proven that the HCV infection is blood-borne and spreads mainly (40–80%) by horizontal transmission, but there would be unknown significant risk factors [24–27]. It is reported, also, that the contribution of HCV infection to post-transfusion hepatitis varies widely in different countries [27 – 29]. In the present study, the incidence of post-transfusion hepatitis C was 24.6% (15/61), which strongly suggested that blood transfusion would be a very important route of HCV transmission in China. Moreover, another multi-centric prospective study, performed in the recipients of transfusions in five Chinese university hospitals in 1995, showed quit high rates of seroconversion to anti-HCV (data not shown), which also suggests a close relationship between HCV infection and blood transfusions in China. The present results indicate that, even though the anti-HCV screening of blood donors has been conducted since July, 1992 in China, much more strict measures for donor screening are urgently needed. The following steps should be important for preventing post-transfusion HCV infection. First, anti-HCV detection kits with higher sensitivity and specificity should be used for donor screening. Secondly, the blood donation from volunteers should be advocated strongly. As are preceded by excellent outcomes achieved in Japan, West Europe and the United States [30–33], reducing the incidence of post-transfusion hepatitis C may be a key issue to keep HCV infection under control in China. In conclusion, besides HBV infection, HCV infection is also endemic in China. Much more attention should be focused on this here-to-fore underestimated risk, lest another serious public-health problem should develop in the foreseeable future in China.
Acknowledgements The authors thank Professor Hiroshi Suzuki, the Dean of Yamanashi Medical University and the President of Miyakawa Memorial Research Foundation, for valuable help and encouragement. This study was supported, in part, by Chinese Medical Board of New York.
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